Incidently, there is a wave of popular python projects in dev python spheres that use types to define validation and serialization: fastapi, typer, etc.

Granted, the python typing system is very limited, and to get complete validation, you'll need more than types as python type hints can't express complex rules.

Also, as the articles mentions, the validation will occur at runtime, it can't in any way make sure the program is valid from mypy checks alone.

Still, it's really nice to define your input data types and contraints in one go.